Bill Clinton reportedly has a buxom blond mistress who visits so often when Hillary Clinton isn’t home in Chappaqua that the former president’s Secret Service detail have given her an unofficial code name: Energizer.

This is according to Ronald Kessler in “The First Family Detail: Secret Service Agents Reveal the Hidden Lives of Presidents,” due Aug. 5 from Crown Forum.

Kessler is no stranger to the controversies surrounding the Secret Service.

He broke the story that Secret Service agents protecting President Obama in Cartagena, Colombia, hired prostitutes, and put the president in jeopardy.

The book, portions of which I’ve obtained, says none of the normal protocols is followed when Energizer arrives in her SUV, sometimes just minutes after Hillary has left the Westchester house.

Kessler quotes a supervisor informing a new agent: “You don’t stop her, you don’t approach her, you just let her go in.”

Energizer, who is described as charming and friendly, sometimes brought cookies to the agents, according to the book excerpts.

One told Kessler: “It was a warm day, and she was wearing a low-cut tank top, and as she leaned over, her breasts were very exposed. They appeared to be very perky and very new and full … There was no doubt in my mind they were enhanced.”

Kessler also reports that Hillary’s Secret Service detail informs Bill’s Secret Service detail when the former first lady is coming home, so Bill has time to get Energizer off the property and clean up any evidence.

But once, the warning came late. “The agents had to scramble to get Energizer out of there so there wasn’t some kind of big confrontation.”

Kessler also reveals that Hillary is routinely rude to the agents who are sworn to take a bullet for her.

“Because she is so nasty to agents and hostile to law enforcement officers and military officers in general, agents consider being assigned to her detail a form of punishment,” Kessler wrote.

And they don’t get any cookies.

Bill’s representatives did not answer requests for comment.

Nick Merrill, a spokesman for Hillary, has been busy dealing with allegations in Ed Klein’s “Blood Feud,” about the supposed animosity between the Clintons and the Obamas.

When asked for a comment on Kessler’s tome, Merrill replied, “Another book?”